For example, patent document 1 discloses a prior art motor used as a drive source of a power window device installed on a vehicle or the like. The motor includes a rotation shaft that is driven and rotated, a worm shaft of a speed reduction mechanism that reduces the speed of rotational driving force transmitted from the rotation shaft, and a clutch. The rotation shaft and the worm shaft are connected by the clutch. The clutch includes an annular collar and a driving-side rotor, a driven-side rotor, a rolling element, and a retainer (referred to as support member in patent document 1), which are located at an inner side of the collar. The driving-side rotor rotates integrally with the rotation shaft. The driven-side rotor rotates integrally with the worm shaft. The rolling element has, for example, a circular cross section. The retainer holds the rolling element. The driven-side rotor includes a control surface opposed to the inner circumferential surface of the collar. The rolling element is located between the control surface and the inner circumferential surface of the collar. The retainer includes two circumferential holders configured to rotate in a circumferential direction and holding the rolling element at opposite sides in the circumferential direction.
In a motor including a clutch such as that described above, when the rotation shaft is driven and rotated to rotate the driving-side rotor, a rolling element releaser of the driving-side rotor pushes the rolling element via the retainer (circumferential holders) in a rotation direction. As a result, with the rolling element separated from the control surface and the collar, the rolling element, the retainer, the driven-side rotor, and the worm shaft integrally rotate, and the vehicle window glass opens and closes based on the rotation of the worm shaft. When the rotation shaft (driving-side rotor) is in a non-driven-rotated state, the rolling element is held and wedged by the control surface of the driven-side rotor and the inner circumferential surface of the collar so that rotation of the driven-side rotor is prevented (locked). This limits a situation in which the vehicle window glass is opened and closed, for example, by an external force other than the motor driving force.